First off.....a group of Shadowhunters go back to recover Sebastian's body only to find it gone. Is he still alive?

Maybe! Valentine is definitely dead, but Sebastian . . . well, that remains to be seen.

When Sebastian and Clary visit Ragnor Fell, the smoke curling from the cottage chimney formed the pattern of lopsided hearts. Why did it do this?

As Magnus says later, he was watching Sebastian and Clary out the window, and saw Sebastian trying to take her hand. The smoke was just Magnus making fun of them.

Speaking of our favorite warlock, at the very end of the novel, he is found speaking to a "girl in a white dress with a cloud of curly hair." Clary recognizes something familiar about her, but can't quite place it. Who is she?

She is Tessa, from the Infernal Devices series.

We, at The Reader's Quill, have always been big Simon supporters. However, we are a bit worried about him. Are there any side effects to having the Mark? How will it affect his life?

The thing about Simon is that his arc is almost a superhero arc. He’s gone from being a normal, nerdy guy to a well-nigh invincible supernatural creature. How will that affect his life? Severely, I would imagine. I doubt he’ll ever have the normal life he wants. I actually started writing a short story that takes place after City of Glass and involves Simon having to take on a town of evil vampires. We’ll see where that goes.

Also, who does Simon choose Maia or Isabelle?

At the end of the book? Neither. After the end of the book? I haven’t written that yet!

Now let's talk business - Clary and Jace. Where do they go from here?

Back to New York, I assume. After that — who knows what happens?

You mentioned before that Shadowhunters tend to get married earlier since they lead shorter lives. Are Clary and Jace headed down this path?

Not that early. I meant early twenties, not teens. If they’re still together in five years, I am sure they would discuss getting married.

At the end of City of Glass, Clary refused to help the Seelie Queen, but not before the queen told her that she may have heard half truths from Jocelyn. What did her mother embellish?

Maybe she embellished nothing. The Seelie Queen’s talent is implying without saying — she can’t lie, but she certainly can mislead. The important thing in that scene is the choice Clary makes, her decision that she doesn’t care, or doesn’t care enough to get embroiled with the Seelie Queen to find out.

We loved City of Glass so much, Cassie, but we were curious.... will we ever get to see our favorite characters again? Perhaps a book four?

There’s never going to be a book four of the Mortal Instruments. The story of the Mortal Instruments is over — the Instruments are retrieved, Valentine’s dead, it’s done. If I ever do decide to write more books about these characters in this time period, it would most likely focus on some of the more minor characters — Simon, for instance. Clary and Jace are done being my main protagonists. Haven’t they been through enough?Make sure to check out Cassie's City of Glass playlist over at our music site, The Musical Menagerie.